Alarm setting mechanism for alarm clocks



Dec. 26, 1961 G. CLAY ALARM SETTING MECHANISM FOR ALARM CLOCKS FiledJune 20, 1958 2 4 Fig. 0-

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(km cz =c CLAY ATORNIEN$ United States Patent 3,014,338 ALARM SETTINGMECHANISM FOR ALARM CLOCKS George Clay, Cricklcwood, London, England,assignor to S. Smith & Sons (England) Limited, London, England, aBritish company Filed June 20, 1958, Ser. No. 743,295 Claims priority,application Great Britain June 21, 1957 2 Claims. (Cl. 58--22) Thisinvention relates to alarm setting mechanisms for alarm clocks of thekind in which a rotatable setting element is arranged to impartrotational adjusting movement to a cam follower and to an indicatinghand, which two parts are normally fixed and which follower co-operateswith a cam rotated by the clock movement so that when a part of the camis brought by its rotation opposite a part of the cam follower, thealarm mechanism is set into operation. It is usual, with such anarrangement, for a spindle to which the cam follower and hand areattached to pass through a boss on a wheel constituting a part of thetransmission which drives the cam and thus there may be a tendency forthe cam follower to creep from the position into which it has been set.An object of the present invention is to prevent such creep takingplace.

According to this invention, an alarm setting mechanism of the kindreferred to is characterised in that said cam follower is provided witha cylindrical boss, which is arranged opposite a cylindrical boss formedon a fixed part of the clock, which two cylindrical bosses aresubstantially the same in diameter and are closely encircled by theconvolutions of a helical spring, the arrangement being such that anytendency for relative movement between the two bosses due to creep,causes the convolutions around the fixed boss to tightly grip it thuspreventing the creep, while relative movement which takes place insetting the alarm has the tendency to unwrap the spring from the bosseswhereby the setting movement is not substantially resisted.

In one construction according to the invention, an alarm setting knob isfixed to an axially movable spindle to which is fixed a pinion so thatat one limit of axial movement, the pinion engages another pinion fixedto a second spindle carrying the indicating hand traversing a settingscale for the alarm and at the other limit of axial movement it engagesa pinion in a transmission for setting the hands of the clock.

The pinion attached to the second spindle may have a boss whose endforms a cam face, formed with two similar notches spaced apart by 210about the spindle, which notches have one radial face at right angles toa plane normal to the spindle axis and the other radial at an angle tosaid plane and which second spindle extends through a cam member, havingteeth capable of dropping into the said notches.

The cam member may be formed at the end of a hollow boss fixed to atoothed wheel constituting a part of the transmission for driving theclock hands.

The aforesaid spindle may pass through this hollow boss and has thealarm pointer fixed to its extremity.

A shoulder may be formed between the cam member and the hollow bosswhic'nris engaged by an alarm release spring which tends to press thecam towards the cam follower.

' The pinion to which the cam follower is fixed may be provided with acylindrical boss which abuts a fixed boss on a part of the clock frame,the diameters of which two bosses are substantially the same,'and theyare encircled by a helical spring having convolutions which lightly andfrictionally engage the surface of the two bosses. The direction ofwinding of this spring is such that when 3,014,338 Patented Dec. 26,1961 the manipulating knob is moved in a direction to set the alarm handthe spring tends to unwrap; when, however, the hand has been set, thetendency for the cam follower to be rotated by the clock movementtightens the spring around the fixed boss, thereby holding the camfollower against any tendency to be moved from its set position by therotation of the cam, which is of course in frictional engagement withit.

The following is a description of one form of alarm setting mechanismfor alarm clocks according to the invention, reference being made to theaccompanying drawings in which:

FIGURE 1 is a diagrammatic side elevation of the setting mechanism;

FIGURE 2 is a plan view of the cam follower shown in FIGURE 1; and

FIGURE 3 is an under plan view of the cam shown in FIGURE 1.

Mounted between the front and back plates 10 and 11 of the clock arevarious toothed wheels of the alarm operating mechanism (not shown) andvarious toothed wheels 12, 13 and 15 associated with the transmissionfor driving the clock hands (not shown). One of the wheels 12 has fixedthereto a wide pinion 14 which drives the toothed wheel 15. The toothedwheel 15 has a hollow hub portion 16 the lower end of which is formedwith a cam member 17. A spindle 18 extends through and is rotatable in ahollow hub 16. The upper end of the spindle 18 extends through the frontplate 10 and has attached to its extremity a pointer 19 which traversesan alarm setting scale (not shown). The lower extremity of the spindle18 projects below the cam member 17 and through a pinion 20 to which itis fixed. The pinion is provided with cylindrical boss 21 which abutsanother cylindrical boss 22 of the same diameter which is formed on backplate 11. The cylindrical surfaces of the two bosses are encircled by ahelical spring 23. The upper face of the pinion 20 is formed with a camfollower 24. The pinion 20 may be engaged by an axially movable pinion25 fixed to a spindle 26 provided with a manipulating knob 27. Thespindle 26 is reciprocable in a bearing 28 attached to the back plate11. At the upper limit of its movement the pinion 25 is brought out ofengagement with the pinion 20 and into engagement with the toothed wheel13 which is mounted on shaft 41 journaled in plates 10 and 11 and formspart of the transmission to the clock hands whereby the hands may beset.

The spindle 18 is fixed against axial movement and the toothed wheel 15and its hub 16 and cam 24 may move axially upon it. The enlarged camportion 17 provides a shoulder which is engaged by a spring blade 29,defiection of which in a downwards direction releases the alarmmechanism. Spring blade 29 may be curved as at 40 to allow the passageof axially movable pinion 25 or may yield sufliciently to allow pinion25 to mesh with toothed wheel 13. The spring blade also serves tomaintain the cam 17 and cam follower 24 in contact. The direction ofwinding of the spring 23 is such that when the manipulating member 27 isin a position in which the pinions 20 and 25 are in engagement and themanipulating member is rotated in a direction to set the pointer 19 andcam follower 24, the spring tends to unwrap. When, however, the pointerhas been set any tendency there may be for the cam follower to berotated out of its adjusted position by the spindle 18 tightens thespring around the two bosses 21 and 22 and since the latter is fixed thespindle 18 is prevented from rotation and from changing the setting ofthe cam follower.

As will be seen from FIGURE 2, the upper face of the cam follower 24 isprovided with two notches 30 spaced apart by about 210, each of whichnotches is provided with a radial face 31 which is at right angles to aplane normal to the spindle axis and the other face 32 is inclined to aplane normal to the spindle axis. The cam member 17 is provided withinclined teeth 33 so disposed that during one part of rotation of thecam they can drop into said recesses 30 after passing over the ends ofthe faces 31, whereby axial movement is imparted to the cam member bythe spring blade 2-9 thus releasing the alarm mechanism. The inclinedportion of the teeth 33 eventually engage the inclined faces 32 wherebythe alarm mechanism is reset.

While there have been described above What are presently believed to bethe preferred forms of the invention, variations thereof will be obviousto those skilled in the art and all such changes and variations whichfall within the spirit of the invention are intended to be covered bythe generic terms in the appended claims, which are variably worded tothat end.

I claim:

1. An alarm clock setting mechanism for alarm clocks comprising incombination with a clock mechanism having a frame and an alarm, atoothed wheel having a hollow hub portion the end of which is formedwith a cam member, a spindle which extends through and is rotatable insaid hollow hub, an alarm setting indicating pointer attached adjacentone end of said spindle, a pinion having a cam follower on one side anda first cylindrical boss on the other, a second cylindrical boss of thesame diameter as and substantially aligned with said first boss andfixed to the frame, the other end of said spindle projecting throughsaid hollow hub, through said pinion and into said fixed poss, a helicalspring encircling the cylindrical surfaces of the two bosses, arotatable setting element connected to impart rotational alarm settingadjustment to said cam follower, said helical spring encircling bothsaid bosses in such a direction that any tendency for relative movementbetween the two bosses in one direction due to creep causes theconvolutions around the fixed boss to grip it tightly and prevent creepand any relative movement in the opposite direction which takes place insetting the alarm tends to unwrap the spring from the bosses uponrotational alarm setting adjustment of said cam follower by said settingelement, an alarm release spring, a shoulder formed between the cammember and said hollow hub, said shoulder being engaged by said alarmrelease spring which tends to press the cam towards the cam follower.

2. The combination set forth in claim 1, said earn follower having twosimilar notches spaced apart by 210 about the spindle axis, each notchhaving one radial face perpendicular to a plane normal to the spindleaxis and another radial face at an angle to said plane, said cam havingteeth constructed and arranged to mate with said notches and to actuatesaid alarm release spring and to cause the alarm to sound.

References Cited in the file of this patent UNITED STATES PATENTS871,019 Alford Nov. 12, 1907 1,999,692 Haydon et al Apr. 30, 19352,145,083 Dynes Jan. 24, 1939 2,338,944 Junghans Ian. 11, 1944

